Hydraulic press



Patented May il, 1934i pdl@ d illaims.

My invention has or its object to provide a hydraulic press having a rain, which will be moved through a stroke regulated as to pressure and length and operated by a driving piston having a uniform short stroke. The invention eliminates all the back lash of such presses, which wears and ages the dies and the machine.

The particular object of my invention is to provide a means for limiting the pressureexerted on the ram by the power transmitting fluid to a certain predetermined adjustable degree, which, however, is ample for the ram to perform the work required. This prevents injury to the machine or the dies should the ram meet with a resisting force greater than the said predetermined degree or with some obstruction in its path. Heretofore, presses commonly used could not be controlled as to limits of pressure and as to length of stroke and when a tool or piece of metal obstructed the movement of the ram or the die, the ram would jam the tool or metal into the die or jam the die itself, causing injury and great expense.

Another object of my invention is to provide a means for short-circuiting the power transmitting iiuid when the ram has reached the desired limit of the stroke, or when the predetermined pressure has been obtained, which may occur at any point-in its stroke, and returning the ram to its desired pre-stroke position.

.smother object of my invention is to provide for a quick release behind the ram to allow a speedier return of the ram to a pre-stroke position.

The invention may be contained in structures that vary in their details and, to illustrate a practical application of the invention, I have selected a structure containing theinvention as an example of the various formsof structures that i embody the invention and shall describe the structure selected hereinafter. The structure selected is shown in .the accompanying drawings.

Fig. l illustrates a side view of the punch press. -Fig. 2 illustrates a 'vertical section of the punch press. Fig. 3 illustrates an enlarged view of a section ofthe controlling slide valve. Fig. t illustrates a iront view of the punch press. Fig. 5 illustrates connecting passageways in the wall of the cylinders of the press.

The frame 1 of the punch press, selected for purposes of illustration, is provided with a suitable table 2, above which is located a reciprocable movable crosshead 3. The crosshead 3 is guided in its movements by suitable ways e that are supported by the frame 1.

The machine is provided with a suitable eccentric 8 that is driven by a power shaft 9. A link 10 communicates the movement of the eccentric 8 to the piston 11. The piston 11 is connected to a piston rod v12 having a considerable (Cl. Sli-5415) 4substantially the same with the result that a complete movement ol the piston 11, within its cylinder 13, will ordinarily cause movement oi the piston 15 throughout substantially the lull length of the entire cylinder i4. The cylinders 13 and 14 are connected together by means or the passageways 19 and 2O which connect the opposite ends of the cylinders.

Any fluid maybe used for transmitting the pressures. Preferably` oil is used and is located in a suitable reservoir that communicates with the cylinders to maintain them substantially lled with the oil, with the result that the force exerted by the piston 11 will be directly and positively communicated to the piston 15. The connections between the reservoir and the cylinder 13 is controlled by suitable one-way valves to direct a pressure exerted by the piston 1l into the cylinder 1d to cause movement of the piston 15 and prevent return flow of the uid into the reservoir.

In the particular construction shown, the wall of the cylinder 13 is extended to form the reservoir 22. The reservoir 22 communicates with one end of the cylinder 13 through an opening 23 which is controlled by the oneway spring pressed valve 24 located in the head 25 of the cylinder 13. communicates with the reservoir 22 through the pipe 26. The passageway through the pipe 26 is controlled by the one-way spring pressed valve 2'7. Thus, when the piston 1i is moved towards its head 25, all of the liquid will be forced into the cylinder 14 and, iiany oil is required, to permit substantially free movement of the piston l1, other than that which is supplied irom the cylinder 14 and from below the piston 1'5, such additional oil will be supplied from the reservoir 22 through the pipe 26. Upon the return stroke of the piston il, the oil will be forced below the piston 15 while the oil above the piston 15 will be directed into the cylinder 13 by the passageway 19 and, if any additional oil is required, it will be supplied through the opening 23. Thus the oil within the reservoir 22 will maintain the cylinders full and with the required amount of oil in order to produce posi- The other end of the cylinder 13 tive transmission of the forces that are exerted by the rotation of the shaft 9.

In order to eliminate material transmission of oil to and from the reservoir 22, the volumes of the cylinders, less the volumes of their respective pistons and the portions of the piston rods that move within the cylinders, are substantially equal. Consequently, the piston rod 12 has a considerable larger diameter than the piston rod 16. Preferably, the diameters of the piston rods 12 and 16 have the same ratio as the diameters of the pistons l1 and 15, whereby there will be maintained substantially the same displacement of the iiuid from beneath the pistons when they are caused to move in the direction that the piston rods extend.

In order to insure completion of the strokes of the piston l5, and the production of the desired pressure of the crosshead, the cylinder 13 is slightly larger than the cylinder 14, that is, movement of the piston 1l will cause movement of a quantity of fluid slightly more than that is required to cause the complete movement of the piston 15. In order that the piston 1l may be permitted to complete its stroke, the cylinder 14 is connectedat its ends to the reservoir 22 in order to permit the return of this small excess of oil to the reservoir 22. Thus the cylinder 14 is connected to the reservoir 22 by means of the pipes 30 and 31 having pressure regulating valves. The passageways through the pipes 30 and 31 are controlled by the adjustable spring pressed valves 32 and 33. The valves operate to close small openings located in the ends of the cylinder 14 and the springs 32 and 33 are adjustably compressed to cause the production of the desired pressure by means of the screw bolts 34 and 35. Thus the pressure that is transmitted to the piston 15 may be controlled by the adjustment of the valves 32 and 33 for, if there `should be an unusual resistance to the movement oi'n'the piston 15, the fluid will be allowed to escape through one or the other of the valves 32 and .33, depending on the direction of the movement of the piston 15. The piston l1 may continue to move but the piston 15 may be held statitonary by the resistance if it is in excess to the' pressure as determined by the adjustment of the valves 32 and 33. This provides an exceedingly emcient means for regulating the pressure that may be exerted by the erosshead 3 which is connected to the piston rod 16. Consequently, if the crosshead 3 should meet with an obstruction that might injure the dies, or the tool that may be connected to the crosshead 3, an extreme injurious pressure will be avoided by adjusting the machine so that the pressure, that is transmittable, is limited to slightly greater than that necessary for the machine to perform the required work.

The construction described also lends itself very readily to the control of the stroke of the piston 15 and, consequently, of the crosshead 3. The lengths of the strokes may be varied as may be desired and the points of beginning and ending of the stroke may be also varied. This makes the machine exceedingly efficient to perform various operations and enables the use of a great variety of tools of different lengths or heights. and those which may be operated within certain limitations of pressure. Consequently, the machine is rendered exceedingly versatile in its uses..

Preferably, the machine is provided with a slide valve 38 consisting of a tri-headed piston 39 located in the cylinder 40 and having properly spaced ports 41, 42 and 43. The piston heads are so locad relative to each other as to connect either of the outer of the ports, such as the ports 41 and 43, with the inner of the ports, namely, the port 42. The port 41 is connected to the upper end of either of the cylinders 13 and 14, while the port 43 is connected to the lower end of either of the said cylinders. Preferably, the ports 41 and 43 are connected with the passageways 19 and 20 respectively. The port 42 is connected to the reservoir 22 at a point below the level of the oil in the reservoir.

The slide valve 38 is operated by a member that moves with the crosshead 3. In the particular construction shown, the piston rod 45 of the slide valve, is connected to the lever arm 46 which is supported by means of a suitable bracket 47 on the frame 1 of the machine. The rod 48 is connected to the crosshead 3 by means of a bracket 49. The rod 48 is slidably movable in and guided by means of the bracket 50, which is secured to the cylinder 14. The rod 48 is provided with a pair of fingers or blocks 51 and 52 that protrude so as to engage the lever 46. One of the blocks is located below the lever 46 and the other block is located above the lever 46. When, therefore, the crosshead 3 is reciprocated, the blocks will alternately engage the lever 46 to shift the slide valve at the desired points in the movements of the crosshead 3. The position of the blocks 51 and 52 of the rod 48 determines the time or points in the movement of the crosshead 3 at which the slide Valve will be shifted from one position to the other to connect one or the other of the ports 41 and 43 with the port 42 and, consequently, with the reservoir 22. The blocks 51 and 52 may be adjustably secured in position by the screw bolts 53.

When the slide valve 38 is moved by one or the other of the blocks 51 and 52, it short circuits the oil from the cylinder 13 to the reservoir 22 and, consequently, transmission of pressure to the cylinder 14 ceases until the piston 11 makes its return stroke. Upon the return movement of the piston 11, the Same occurs in the return movement of the piston 15 and, consequently, of the crosshead 3. When the crosshead 3 is lowered by the operation of the piston 15, due to an upv ard stroke of the piston ll, the finger or block 51 will, in the course of such movements, strike the lever 46 which establishes connections between the ports 41 and 42 and, consequently, communication is established between the upper ends of the cylinders 13 and 14 with the reservoir 22 and the oil in the cylinder 13, located above the piston 11, will flow into the reservoir 22 without resistance and the pressure on the piston 15 will cease. This occurs at the completion of the stroke, 110W- ever, giving full opportunity for the production of the required working pressure. The piston 11 will complete. its stroke, ejecting the oil through the passageways formed by the pipes 55 and 56, which are connected, respectively, with the ports 41 and 42, and, upon the return stroke, it will raise the piston 15 until the finger or block 52 strikes the end of the lever 46 whereupon the slide valve will connect together the ports 42 and 43 and conneet the lower ends of the cylinders 13 and 14 with the reservoir 22 through the pipes 57 and 56. The upward movement of the piston l5, and consequently of the crosshead 3, will immediately cease and the surplus oil, located below the piston 11, will pass out through the pipes 56 and 57 to the reservoir 22. Thus .the crosshead 3 may be caused to operate, not only within certain limits of pressure, as determined by the adjustments of the valves 32 and 33. but also within certain heights or between defined horizontal planes. Thus the length of the stroke may be not only varied, but also the relative position of the strokes, with reference to a vertical line, may be varied, that is,

iat

the extreme points of the reciprocatory'movements of the crosshead may be varied as may be desired.

In order to provide return of any oil that may leak by the piston 39, into the ends of the cylinder` Lli) of the slide valve 38, the ends of the cylinder may be connected by suitable small pipes 58 with the reservoir 22 to enable, at all times, free movement of the piston 39 of the slide valve 38.

I claim:

l. In a hydraulic press, a pair of cylinders intercommunicating at their ends, one of the cylinders having a drivfing piston and the other of the cylinders having a driven piston and mechanical means ior driving the driving piston, a fluidl reservoir, the press having a plurality of passageways connected to the fluid reservoir and the ends of the cylinders, one-way valves located in certain of said passageways to permit fluid to enter the ends of the said cylinders from the reservoir, and a slide valve for opening and closing other of the said passageways for permitting free movement of the iiud in the said other of the said passageways at desired. points in the movement of the driving piston and the driven piston actuated by the pressure of the driving piston on the fluid from the reservoir and until the slide valve opens one or the other of the said passageways connected to the ends of the cylinders toward which the driving piston is moved.

2. In a hydraulic press, a pair of cylinders intercommunicating at their ends, one of the cylinders having a driving piston and the other of the cylinders having a driven piston and mechanical means for driving the driving piston, a ilu'id reservoir, the press having a plurality of passageways connected to the uid reservoir and the ends of the cylinders, one-way valves located in certain of said passageways to permit uid to enter the ends of the said cylinders from the reservoir, adjustable one-Way spring pressed valves located in other of the said passageways for permitting fluid under pressure to pass from the ends of the said cylinders to the reservoir when the pressure in the said cylinders exceeds the pressure of the springs, and a slide valve for opening and closing other of the said passageways for permitting free movement of the fluid in said other of the said passageways at desired points in the movement of the driving piston, the driven piston actuated by the pressure of the driving piston on the uid from the reservoir and until the slide valve opens the passageway towards which the driving piston is being moved.

3. In a hydraulic press, a cylinder, a piston located in the cylinder, means for driving the piston, a second cylinder and piston, the ends of the cylinders interconnected, a fluid reservoir, three sets of passageways communicating with the ends of the said cylinders and the reservoir, one set of passageways having one-way valves for permitting iluid to enter the opposite ends of each of the cylinders when the pressure in the ends of the cylinders is less than that in the reservoir, adjustable spring pressed valves located in another of the sets of passageways for permitting the escape of the fluid from the opposite ends of each of the cylinders when the pressure in the ends of the cylinders reach a predetermined amount, a slide valve for opening and closing the third set of passageways at desired points in the movement of the rst named piston to permit free flow of the fluid to the reservoir in the said third set of passageways.

e. In a hydraulic press, a pair of cylinders interconnected at their ends, a driving piston located in one cylinder and a driven piston located in the other of the cylinders, means foractuating the driving piston, a reservoir, the press having passageways connecting the ends of the cylin- 8G ders with the reservoir and passageways for connecting the ends of both cylinders with the reservoir, one way valves located in passageways connecting the ends of the cylinder with the reservoir and having the driving piston therein for admitting fluid from the reservoir to the last named cylinder and preventing the return of the uid from the last named cylinder to the reservoir, and adjustable spring pressed one way valves located in passageways connecting the ends of the other cylinder with the reservoir to permit movement of the fluid from the said other cylinder to the reservoir when the pressure in the cylinder exceeds a predetermined pressure, and preventing movement of the uid from the reservoir to the said other cylinder, and a valve for controlling the passageways connecting the ends of both cylinders with the reservoir, and means for operating the said last named valve to open either one of the said passageways at desired points in the movement of the driving piston.

5. In a hydraulic press, a pair of cylinders interconnected at their ends, a driving piston located in one cylinder and a driven piston located in the other of the cylinders, means for actuating the driving piston, a reservoir, the press having passageways connecting the ends of the cylinders with the reservoir and pasageways for connecting the ends of both cylinders with the reservoir, one way valves located in passageways connect- 11g ing the ends of the cylinders with the reservoir, certain of the said valves operating to admit uid to one of the said cylinders from the said reser- Voir, the other of the said valves for preventing movement of the fluid to the said reservoir, means for adjusting the last named valves for preventing movement of the uid to the reservoir until the pressure of the uid reaches a predetermined point, a valve member for controlling the passageways connecting the ends of both cylinders with the reservoir, and means connected to the driving piston for operating the said valve to open the said passageways at desired points in the movement of the driving piston to direct the i'luid from both cylinders to the reservoir.

6. In a hydraulic press, a pair of cylinders interconnected at their ends, a driving piston 1ocated in one cylinder and a driven piston located in the other of the cylinders, means for actuating the driving piston, a reservoir, the press 13o having passageways connecting the ends of the cylinders with the reservoir and a passageway for connecting the one end of each of the cylinders with the reservoir, one way valves located ,in passageways connecting the ends of the cylinders with the reservoir, certain of the said valves operating to admit uid to one of the said cylinders from the said reservoir, the other of the said valves for preventing movement of the fluid to the said reservoir, means for adjusting the last named valves for preventing movement of the fluid to the reservoir until the pressure of the fluid reaches a predetermined point, and means for controlling the passageway connecting one end of each of the cylinders with the reservoir M5 to open the said last named passageway at desired points in the movement of the driving piston when moving towards the said last named passageway.

FRANCIS J. LAPOINTE. 

